Rheumatoid arthritis is a prevalent disease characterized by chronic inflammation of the synovial membrane lining the afflicted joint. Current treatment methods for severe cases of rheumatoid arthritis include the removal of the synovial membrane, e.g., synovectomy. Surgical synovectomy has many limitations including the risk of the surgical procedure itself, and the fact that a surgeon often cannot remove all of the membrane. The diseased tissue remaining eventually regenerates, causing the same symptoms which the surgery was meant to alleviate.
Radiation synovectomy is radiation-induced ablation of diseased synovial membrane tissue accomplished by injecting a radioactive compound into the diseased synovium. Early attempts to perform radiation synovectomy were limited by leakage of the radioactive compounds from the synovium and into surrounding healthy tissues. Significant leakage of the radioactive compound from the injection site exposed normal tissues to dangerous levels of radiation. Because of these limitations, new radiolabelled colloids were sought which would be kinetically inert and of a sufficient size to restrict leakage.
The preparation of a radioactive colloid by a co-precipitation method is disclosed in U.S. Pat. No. 4,752,464. This method entraps a radionuclide in an iron hydroxide matrix. While compounds as described in U.S. Pat. No. 4,752,464 are useful for radiation synovectomy, their method of preparation is cumbersome in that it requires many chemical manipulations with highly radioactive compounds. The radioactive colloid particles produced by the coprecipitation method are of varied sizes and include sizes which will leak from the site of injection. Further, the radioactive compounds of choice are those with relatively short half-lives, consequently, radioactive colloids prepared by the coprecipitation method have an extremely limited shelf life, and the ability of a physician and patient to schedule therapeutic procedures is highly dependent upon prompt supply and delivery of the products.
Therefore, a method for producing radiolabeled colloids for use in the treatment of rheumatoid arthritis, which would be safe and easy to practice, which would produce colloid particles of a uniform size-distribution, and enable on-site addition of radionuclide and hence be cost-saving and more convenient for use by the daily practitioner is still needed. The present method addresses these needs.